Symphony Warning: Missing argument 1 for fieldEntry_Versions::__construct(), called in /site/symphony/lib/toolkit/class.fieldmanager.php on line 534 and defined

An error occurred in /site/extensions/entry_versions/fields/field.entry_versions.php around line 8

3     require_once(EXTENSIONS . '/entry_versions/lib/class.entryversionsmanager.php');
4     require_once(EXTENSIONS . '/entry_versions/lib/class.domconverter.php');
5     
6     Class fieldEntry_Versions extends Field{    
7         
8         function __construct(&$parent){
9             parent::__construct($parent);
10             $this->_name = __('Entry Versions');
11             $this->_required = false;
12         }
Backtrace
[/site/extensions/entry_versions/fields/field.entry_versions.php:8]
    GenericErrorHandler::handler();
[/site/symphony/lib/toolkit/class.fieldmanager.php:534]
    fieldEntry_Versions->__construct();
[/site/symphony/content/content.blueprintssections.php:229]
    FieldManager::create();
[/site/symphony/lib/toolkit/class.administrationpage.php:602]
    contentBlueprintsSections->__viewNew();
[/site/symphony/lib/toolkit/class.administrationpage.php:559]
    AdministrationPage->__switchboard();
[/site/symphony/lib/toolkit/class.administrationpage.php:413]
    AdministrationPage->view();
[/site/symphony/lib/core/class.administration.php:228]
    AdministrationPage->build();
[/site/symphony/lib/core/class.administration.php:381]
    Administration->__buildPage();
[/site/index.php:25]
    Administration->display();

The extension.meta.xml file for the entry_versions extension is not valid XML: 
Missing default namespace definition.